Trilithic 9580 SST Headend Unit Return Path System

9580 System Overview

Your 9580 Return Path Maintenance System is a single test system that enables you to deal with all aspects of return path upkeep; including both ingress control and system balancing. At the core of the system is the SST Unit, a 0.3 to 42 MHz digitizing spectrum analyzer, which is installed at the headend of your cable system.

The SST Headend Unit monitors all signals arriving at the headend, including reverse signal ﾓtrafficﾔ, noise, ingress and test carriers from the SSR Field Unit(s).

A single SST Unit can monitor up to eight separate headend test points simultaneously which enables you to analyze the condition of each. The SST analyzes test signals and the return spectra separately. It packages measurement results into a data stream that it transmits to the SSR Field Unit(s).

The SSRﾒs are addressed individually (A - F) which allows six of these units to be in operation at any one time. Each of these SSR Field Units transmits up to eight test carriers at usersettable frequencies. The SST measures these test carriers to compute the gain and tilt of the return path. The SSRﾒs can store up to 24 sweep displays which can be reviewed at a later time or uploaded to a PC.

During system testing, the SST sorts out the test carrier measurements for each SSR and tags the data with the individual addresses (A ﾖ F) so that each SSR displays the appropriate information. When the SSR receives its data, it displays the response of the return path as either a line graph or as numeric values for gain and tilt. Ingress and noise data are presented as a spectrum analyzer display.


Software Version:

SSTs, SSRs, CM-8s and ACM-8s which have firmware version 2.00 or higher, are equipped with major new features which were not included in earlier firmware versions. The features include the FAST Mode as well as extra frequency spectrum coverage which includes the AM broadcast band.

Introduction

Any CATV operator who maintains a two-way CATV distribution system knows that many factors can affect the performance of that system. Cumulative noise, signal ingress, incorrect gain or bad flatness all conspire to harm the return path which can lead to loss of service and customer complaints.

You have taken an excellent step toward alleviating the problems of your return path with your purchase of this 9580 Return Path Maintenance System. Trilithicﾒs 9580 is designed to monitor all of the troublesome parameters in a single, simple to use system. The 9580 is part of Trilithicﾒs Guardian Return Alignment System which includes the 9580 SST, 9580 SSR, RSVP Installer Return Test Units and Isometer.

It is more than just a return alignment system, however. The system also monitors the total performance of the return path by evaluating ingress and return noise. With the 9580ﾒs FAST Mode, you can increase the effective scanning rate of the INGRESS Modeﾒs spectrum analyzer. This enables you to catch the transient events. PEAK HOLD enables the Unit to display the highest ingress points in NORM or FAST Modes. This makes the SST a powerful tool for capturing transient ingress. The AVERAGING feature is an option you can get for the SST. It is used in FAST and ZOOM Modes to reduce the noise floor displayed on the SST when measuring CW or common path.

The basic 9580 system consists of two types of equipment:
ﾕ SST Headend Unit
ﾕ SSR Field Unit

A system may include more hardware including additional SSR Field Units, RSVP Installer Return Test Units and a variety of headend options.



SST Headend Unit

The SST Headend Unit is compact; occupying only 3.5" of rack space. It is easy to set up and operate. A single SST Headend Unit can support up to six SSR Field Units at a time with no loss of operating speed.

When it is equipped with Trilithicﾒs optional Test Point Manager (TPM-8), the SST analyzes sweep and ingress signals from u  to eight separate test points individually. It sends the appropriate ingress spectrum and flatness data to each SSR Field Unit to which it is connected.

You may also use Trilithicﾒs Test Point Expander (TPX), which is equipped with one or more TPM-8 cards, in conjunction with a single, specially equipped SST unit to monitor up to sixty four nodes for a relatively low cost.

Even when it is not supporting the SSR Field Units, the SST can function as a monitor for return path quality. In attended headends, the personnel can observe noise and ingress patterns using the SSTﾒs built-in LCD display panel as an aid to troubleshooting.

Unattended locations can be monitored since the SST, when equipped with the Communications Manager option (CM-8 or ACM-8), can send ingress and sweep measurement data via direct connection, phone lines, ethernet or fiber to a PC located in a central office (see INGRESS MANAGER OPERATION MANUAL for more information). Monitoring installations are easily expanded since the Communications Manager enables seven additional SST Headend Units (with the Communications Manager option) to be accessed through one phone line. This means that a total of 64 test points may be monitored without having to reconfigure the equipment connections.




SST 9580 SPECIFICATIONS
 

Frequency	0.3 ﾖ 42 MHz
Input Level Range (return test carriers)	+ 25 to ﾖ 10dBmV for full 50dB  dynamic range in Spectrum Mode
Return Inputs	1 standard, 8 with Test Point Manager
Field Units supported	Up to 6 simultaneously
Sweep Mode	5 ﾖ 42 MHz with 0.25dB resolution
Sweep Mode Resolution BW	25 kHz effective
Input Level Accuracy	± 0.35dB Spectrum Display 50dB dynamic range from 10dB above to 40dB below nominal return level with 1dB measurement resolution
Spectrum Dispersion	Norm (0.375 ﾖ 42) Zoom (0.3 ﾖ 42) in 2.5 MHz increments
Resolution BW	375 kHz in Norm; 50 kHz in Zoom; 375 kHz in Fast (1x); 525 kHx in Fast (4x)
Sweep Rate	20 Hz/node in FAST; 80 Hz/node in 4X
Data Carrier TX Frequency	50 to 53.75 and 70.00 to 75.75 MHz Optional 80 - 90 MHz
Data Carrier TX Level	+ 23 to + 55dBmV continuously adjustable
Data Carrier Spurious	ﾖ 60dBc
Modulation	FSK with 38.4 kbps data rate
Data Carrier B.W.	150 kHz at ﾖ 20dBc, 475 kHz at ﾖ60dBc
Remote Access	Via RS-232 or modem for all displays (with Communications Manager)
Display	64 x 128 pixel graphic LCD w/backlight

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